What does "It was my summer job" mean here?

Question

I would like to know what "It was my summer job" means in the following sentences:

‘So Charlie boy,’ Johnno says, ‘tell us. How did you two first meet?’

I think at first he means Charlie and I. Then I realise he’s looking between Charlie and Jules. Right.

‘A millions years ago . . .’ Jules says. She and Charlie raise their eyebrows at each other in perfect unison.

‘I taught her to sail,’ Charlie says. ‘I lived in Cornwall. It was my summer job.’

‘And my dad has a house there,’ Jules says. ‘I hoped if I learnt he might take me out on his boat with him. But it turns out taking your sixteen-year-old daughter for a sail along the South coast wasn’t quite the same as having your latest girlfriend sunbathe on the prow in St Tropez.’ It comes out more bitterly than I think she might have intended. ‘Anyway,’ she says. ‘Charlie was my instructor.’ She looks at him. ‘I had a big crush on him.’

• Lucy Foley, The Guest List, Chapter 12

This is a thriller novel published in 2020 in the United Kingdom. One hundred and fifty guests would be gathering at some remote and deserted fictional islet called Inis an Amplóra off the coast of the island of Ireland to celebrate the wedding between Jules (a self-made woman running an online magazine called The Download) and Will (a celebrity appearing in a TV show program called Survive the Night). The day before the actual wedding day, Hannah, the wife of Charlie (Jules' friend), arrived at the island and is now at the dinner party for the rehearsal dinner with only some selected guests. And during the party, Johnno, Will's friend, asks Charlie and Jules as to how they came to meet each other in the first place. At first, Hannah thinks the question is directed to Charlie and herself, but soon realizes that it is for Jules and Charlie.

In this part, I wonder what he means by his "summer job." Does he mean that he worked as a sailing instructor in summertime, and worked in other profession in wintertime, such as a skiing instructor?

Or, would it be close to that he was not permanently hired, but only worked as a part timer in summertime, probably for just one summer rather than for every summer of each year?

I am just wondering what "summer job" would mean to English speakers.

Answer 1

Some people in academia, usually students, may take a temporary job in the long summer vacation to earn money. This is called a summer job. Teachers or other employees at schools and universities can also do this to make extra money.

Really, if you have regular employment with a large gap during the summer, you can call any temporary position you hold then a summer job, but most people would expect it to be a student who is usually at school or university.